Solar heating system and component

ABSTRACT

A solar system heating component is provided for use in a solar heating system. The heating system comprises a solar collector structure operatively connected to a heat-dissipating structure for using the heat energy which the system produces. Refrigerant is used in the system. The refrigerant is boiled in the collector and condensed in the heat dissipating structure. The solar heating system component is located downstream from the heat dissipating structure and prevents flow of liquid refrigerant back to the collector structure when the temperature in the system rises to a predetermined level. The component also includes other structure including a sight glass, servicing structure and means for mounting auxilliary components.

BACKGROUND OF THE INVENTION

Solar heating systems in the past have been completely filled with acollector fluid, except for a small expansion volume in the surge tank.

The present solar system departs from past practice in one aspect inthat a refrigerant, such as the fluorinated hydrocarbons, is used as thecollector fluid. Only the collector is filled with liquid refrigerant,the balance of the system containing refrigerant gas according to thepressure-temperature relationship of the refrigerant. Normally, thereare no pressure reducing valves or pressure regulating valves used inthe system. The entire system being basically under the same pressure,such control devices may be dispensed with. However, this is not toexclude the use of such structures under certain conditions. Thepressure will be determined by the condensing temperature in the heatdissipator.

In past practice, sensible heat of the collector fluid is raised in thecollector as heat is picked up. The collector fluid is then circulatedby a pump (using some energy) to a heat exchanger or heat dissipating orstorage device.

In the present invention, latent heat of the refrigerant is picked upcausing the liquid refrigerant to "boil" and change to vapor accordingto the amount of heat picked up. Vapor pressure immediately travels tothe heat dissipating device where it condenses and returns as a liquidto the collector, this being a continuous procedure as long as heat isbeing absorbed by the collector.

Now, since latent heat is being used for heat movement instead ofsensible heat, if the load at the heat dissipator is equal to the heatinput at the collector, the pressure in the system will remain constantand not increase. Therefore, the collector plate temperature can remainlower than in old style systems where sensible heat is picked up. Sincethe Delta T in the collector is greater, the efficiency of a collectorcan be much greater than for old style collector fluid charged systems.

Also, the response to sudden bursts of sunlight is almost instantaneousin a refrigerant charged system and it will be picking up andtransferring usable heat before the old style collector fluid chargedsystem can get started.

Whenever the heat dissipator is located above the collector, acirculating pump can usually be eliminated. When desired to locate theheat dissipator below or near the same height as heat pick up, a smallrefrigerant circulating pump is used. However, since latent heat of therefrigerant is used instead of sensible heat, a relatively small weightof refrigerant needs to be circulated and very little power is required.

A refrigerant charged system is very useful in picking up an abundanceof "low-grade" heat for use in heat pumps. Heat may be transferred fromthe ground or storage tanks or phase change materials for use in heatpumps with the expenditure of very little or no energy.

Obviously, this system may be used for picking up heat and moving itinside to a radiator, or fan coil, or heat dissipating plate, or waterheater, or heat exchanger primary, or for storage in water, masonry,phase change materials and the like.

The present invention comprises a component for such a system which willcontrol flow of refrigerant in the system to allow flow only as suchtimes when the temperature, and consequently the pressure, of therefrigerant is low enough so that the system may be operated safely. Thecomponent is located in the liquid refrigerant return line between theheat dissipating structure and the collector structure. Athermostatically controlled valve is provided in the component. Thisvalve closes at a predetermined temperature causing a stoppage of flowof liquid refrigerant back to the collector structure from the heatdissipating structure. This results in all refrigerant being condensedinto the heat dissipating structure whereupon the system becomesinoperative. Therefore, the maximum system temperature is regulatedwithout external means or controls or external wiring.

The component provides additional structure including a convenient valveevaluating, charging and servicing for the system and provides aconnection for a permanent pressure gauge if desired. The component isuseful in installing, servicing, checking as to the amount of charge andcontrolling the maximum system temperature and pressure.

SUMMARY OF THE INVENTION

A closed solar heating system is provided. The system includes a solarcollector structure, heat dissipating structure and means forcirculating a refrigerant heat transfer medium in gaseous form from thecollector structure to the heat dissipating structure and in liquid formfrom the heat dissipating structure to the collector structure. All ofthese components are connected together in operative relationship. Thesystem is charged with a refrigerant heat transfer medium. The heatdissipating structure has a sufficient volume capacity to store all ofthe heat transfer medium in the system when such medium is in liquidform. A thermostatically operated valve is provided in the means forcirculating a refrigerant heat transfer medium in liquid form from theheat dissipating structure to the collector structure. Thethermostatically operated valve is open to permit flow of liquidrefrigerant therethrough when the temperature thereof is below apredetermined level. The thermostatically operated valve closed when thetemperature of the liquid refrigerant passing therethrough is above thepredetermined level.

IN THE DRAWING

FIG. 1 is a diagramatic view in elevation of one embodiment of a solarheating system including the component of the present invention; and

FIG. 2 is a elevational view of the component for the FIG. 1 system.

Referring to FIG. 1, the solar energy system 10 comprises a solarcollector 12 which includes an internal tubular structure. The inlet andoutlet of the collector 12 are connected to, respectively, conduits 14,16. A heat dissipating structure 18, which includes a coil 19 and areceiver 21 connected to the outlet thereof, is provided above thecollector 12. The coil 19 may be used to dissipate heat in any desiredway, as by use of fans, immersion in water, soil or other media and thelike. The conduits 14, 16 are connected to the coil 19.

Alternately to coil 19 and receiver 21, a vessel may be connected to theoutlet of collector 12 and serve as a condenser. The vessel may surrounda coil through which a heat transfer medium flows.

In the present invention, standard refrigerant fluid suitable for use inrefrigeration, normally fluorinated hydrocarbons, is used as the heatexchange medium in the system. The refrigerant changes from a liquid toa gas in the collector 12. In essence, the refrigerant boils. Thus, itis the latent heat causing evaporation, not sensible heat, which isabsorbed by the refrigerant in the collector 12. As there is no greatchange in temperature upon evaporation, the collector will run coolerthan conventional systems. Also, less amounts of fluid need be pumped,when pumping is necessary, thereby reducing pump size and energy usethereof, because more heat is absorbed in a small volume of medium.

When the evaporated refrigerant circulates through the coil 19, itcondenses into a liquid. In so doing, it gives off the latent heat asdesired.

The collector 12 is of the type wherein the coils are essentiallyflooded with liquid refrigerant leaving only a small space at the upperportion to receive gaseous refrigerant which boils off from the liquidrefrigerant. The collector is of generally conventional construction. Itcomprises a casing 20 having a transparent plate 22 through which thesun's rays pass. Inside the casing 20 and behind the plate 22 is a metalplate 24, normally blackened to result in maximum absorption of sunrays.

A tubular structure 26 is secured on the face of metal plate 24 and heattransfer relation thereto. The tubular structure 26 preferably comprisesa plurallity of parallel tubes connected at each end by a tubularmanifold. Conduit 16 is connected to the inlet of the tubular structureand conduit 14 is connected to the outlet of the tubular structure.

As will be appreciated, when collector 12 is positioned as in FIG. 1,liquid refrigerant floods a major portion of the tubular structure whilegaseous refrigerant may boil off the top thereof and into conduit 14. Athin, flat vessel could be used instead of a tubular structure 26. Onthe other hand, a sinuous tubular structure would be undesirable becausethe gaseous refrigerant would have to move through liquid refrigerant.As will be appreciated, several collectors 12 may be connected togetherin a bank.

An off-on valve 28 is provided between the outlet of coil 19 and theinlet of collector 12. The valve 28 is preferably solenoid operated topermit electrical control thereof. The valve 28 may be closed at timeswhen it is desired to control heat transfer. Refrigerant which vaporizesin the collector flows through the coil 19 and is condensed to a liquid.The liquid cannot flow back to the collector 12 when valve 28 is closed.Coil 19 and receiver 21 have sufficient capacity to hold all of theliquid charge. When collector 12 empties, heat transfer ceases.

The component 30 is provided in conduit 16. The component 30, as shownin FIG. 2, includes a small closed vessel 32 having a sight glass 34. Afloat 36 is provided to illustrate the liquid level in the system. Thesight glass 34 should be positioned at the same level as the top 38 oftubular structure 26. Then when the system is charged to the sightglass, the collector will have a proper level of liquid refrigerant.

A thermostatically controlled valve structure is provided within thevessel 32. This structure includes a wall structure 42 located adjacentthe lower end of vessel 32. The wall structure 42 extends entirelyacross the vessel 32 and provides a fluid seal between upper compartment44 and lower compartment 46 excepting for central valve opening 48. Avalve element 50 is pivotally in opening 48. When the valve element 50is tilted as shown in FIG. 2, liquid refrigerant may pass from uppercompartment 44 into lower compartment 46 and then through conduit 16 toflow back to the lower portion of tubular structure 26 in collector 12.However, when valve element 50 is pivoted to be in line with wallstructure 42, compartments 44, 46 are effectively sealed from each otherand liquid refrigerant will stop flowing. Gaseous refrigerant whichsubsequently condenses in coil 19 will be trapped in this coil and thereceiver 21. As will be recalled, the heat dissipating structure 18 hassufficient capacity to store all of the liquid refrigerant in thesystem. Thus, as liquid refrigerant continues to boil in collector 12,it will condense in coil 19 and be trapped in coil 19 and receiver 21.Ultimately, all of the liquid refrigerant in collector 12 will boil offand be condensed in the coil 19 and remain in the coil and receiver. Thesystem will then be shut down.

The means for closing or opening valve element 50 include a thermostaticelement 52 mounted on a bracket 54. The bracket 54 is mounted on wallstructure 42. Element 52 includes a power capsule 56 which containsconventional thermostatically expansionable material. A piston 58extends from capsule 56 into contact with the upper surface of the valveelement 50 off-center from the pivotal mounting 60 thereof. A coilspring 64 has its upper end attached to bracket 54. The lower end 66extends into slot 68 of element 70 which is secured to the upper surfaceof the valve element 50. The piston has a bracket 72 at the end thereofand is pivotably mounted to element 74 at 76.

The spring, in its normal relaxed position as shown in FIG. 2, normallypivots the valve element 50 out of alignment with the wall structure 42as shown in FIG. 2. When the temperature of the return liquidrefrigerant reaches a sufficient elevation, piston 58 is forced out ofcapsule 56 downwardly to cause closure of the valve element into aposition in alignment with wall structure 42. This effectively seals thecompartments 46, 48 as previously discussed.

In operation of the system, liquid refrigerant is boiled in thecollector 12 when the sun rays shine thereon. The gaseous refrigerantpasses to the coil 19 as a consequence of its own pressure. It is notpumped by external means. The gaseous refrigerant condenses in coil 19,thus giving off heat. The liquid refrigerant is then returned tocollector 12 by means of gravity, it being noted that coil 19 is locatedabove collector 12. If coil 19 is located below collector 12, then asmall refrigerant pump is necessary to move the liquid refrigerant.

Should the system temperature raise to a predetermined, undesired level,valve element 50 will close. Liquid refrigerant will then collect incoil 19 and receiver 21 until all of the refrigerant has boiled offcollector 12 thus effectively closing the system down.

What I claim as my invention is:
 1. A closed solar heating systemcomprising a solar collector structure, heat dissipating structure, andmeans for producing the circulation of a refrigerant heat transfermedium in gaseous form from the collector structure to the heatdissipating structure to the collector structure, all connected togetherin operative relationship, a refrigerant heat transfer medium in thesystem, said heat dissipating structure having a volume capacitysufficient to store all of the refrigerant heat transfer medium in thesystem when said medium is in liquid form, a thermostatically operatedvalve provided in the means for producing the circulation of arefrigerant heat transfer medium in liquid form from the heatdissipating structure to the collector structure, said thermostaticallyoperated valve including means to normally hold the valve in the openposition when the temperature of the liquid refrigerant passingtherethrough is below a predetermined level, said thermostaticallyoperated valve including means responsive to temperature to causeclosing of the valve when the temperature of the liquid refrigerantpassing therethrough rises above the predetermined level, said solarcollector being located to receive sun rays, said heat dissipatingstructure being effective to transfer heat to a heat receiving mediumduring periods of sunlight.
 2. A closed solar heating system as in claim1, further characterized in that the refrigerant heat transfer medium isa fluorinated hydrocarbon.
 3. A closed solar heating system as in claim1, further characterized in the provision of an on-off valve in themeans for circulating the liquid heat transfer medium between the heatdissipating structure and the collector structure.
 4. A closed solarheating system as in claim 1, further characterized in the provision ofa closed vessel in the means for circulating the liquid heat transfermedium between the heat dissipating structure and the collectorstructure, wall structure within said closed vessel dividing the vesselinto two compartments, said thermostatically operated valve beingmounted on said wall structure, said wall structure including a valveopening, said thermostatically operated valve including a valve elementbeing movable to a position out of alignment with said wall structure topermit liquid refrigerant to flow through said opening, said valvestructure being movable to a position in alignment with said wallstructure to prevent movement of liquid refrigerant through saidopening.
 5. A closed solar heating system as in claim 4, furthercharacterized in the provision of a sight glass and float elements onsaid vessel, said sight glass being located in substantial alignmentwith the upper portion of said collector structure so as to permitobservation of the level of liquid refrigerant in the upper portion ofsaid collector structure.
 6. A closed solar heating system as in claim5, further characterized in the provision of additional valve structureon said vessel, said additional valve structure permitting charging orevacuating the solar heating system with refrigerant heat transfermedium.
 7. A closed solar heating system as in claim 6, furthercharacterized in that the additional valve structure includes means formounting a pressure gauge.
 8. A closed solar heating system as in claim7, further characterized in that the additional valve structure includesmeans for opening the interior of said vessel to either the means formounting a pressure gauge or the means for evacuating or charging thesystem.